<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      html,
      body,
      .app {
        width: 100%;
        height: 100%;
        display: flex;
        flex-direction: column;
        margin: 0;
      }
      .header {
        width: 100%;
        height: 50px;
      }
      .main {
        display: flex;
        width: 100%;
        flex: 1;
      }
      .left {
        width: 150px;
        height: 100%;
        background-color: #ccc;
      }
      .mid {
        position: relative;
        flex: 1;
        height: 100%;
      }
      .mid .banner {
        position: absolute;
        top: 400px;
        left: 500px;
        width: 150px;
        height: 150px;
        background-color: pink;
      }
      .right {
        width: 150px;
        height: 100%;
        background-color: #999;
      }
    </style>
  </head>
  <body>
    <div class="app">
      <div class="header"></div>
      <div class="main">
        <div class="left"></div>
        <div class="mid">
          <div class="banner"></div>
        </div>
        <div class="right"></div>
      </div>
    </div>
    <!-- <script src="./jquery_offset.js"></script> -->
    <!-- <script src="./runPromiseInSequence.js"></script> -->
    <!-- <script src="./reduce.js"></script> -->
    <script src="./compose.js"></script>
    <!-- <script>
      const oBanner = document.getElementsByClassName("banner")[0];
      console.log($.offset(oBanner));
    </script> -->
  </body>
</html>
